/Engine/Source/Runtime/Engine/Public/MaterialShared.h
A global map from a material's static parameter set to any shader map cached for that material. Note: this does not necessarily contain all material shader maps in memory. Shader maps with the same key can evict each other. No ref counting needed as these are removed on destruction of the shader map.
static [TMap](API\Runtime\Core\Containers\TMap)< [FMaterialShaderMapId](API\Runtime\Engine\FMaterialShaderMapId), [FMaterialShaderMap](API\Runtime\Engine\FMaterialShaderMap) * > GIdToMaterialShaderMap;